The invention relates to an electron-emitting component with a field-emitting cold cathode comprising a substrate and a cover layer with a diamond-containing material. Such a component can suitably be used in flat display screens, for generating light, in electron microscopes and in other fields of application in which cold cathodes are employed.
A component of the type mentioned in the opening paragraph generally comprises, in addition to the cold cathode, an anode which is arranged at some distance from the cold cathode. An electric field is applied between the anode and the cathode so as to bring about electron emission from the cathode surface. The electron current can be controlled by a control device. To bring about a cold emission, that is, an electron emission without heating the cathode, it is necessary to apply very high field voltages between the anode and the cathode or to construct the surface of the cold cathode in such a manner that the electrons have a low work function.
Layers of diamond-containing material can very suitably be used as electron-emitting cover layers of cold cathodes, because they have a low work function and the energy of the emanating electrons exhibits a low degree of scattering. In addition, diamond exhibits an excellent heat conductance, chemical inertness and resistance to wear.
In EP-A-0 709 869 a description is given of a diamond field emitter for emitting electrons at low voltages, which emitter comprises a substrate and, deposited on said substrate, a diamond-containing material which is characterized by a line in the Raman spectrum for diamond at 1332 cm.sup.-1, which has been broadened to a half-width value of 5-15 cm.sup.-1, said diamond-containing material emitting electrons with a current density of at least 0.1 mA/mm.sup.2 in a field of 25 V/.mu.m or less, and said emitter further comprising means for electrically contacting this field emitter. The diamond-containing material comprises "diamond islands" having a grain-size diameter below 10 .mu.m, which diamond islands preferably have sharp tips or facets.
In the case of the above-mentioned surface morphology, electron emission preferably takes place from the tips of the relevant diamond islands. As a result, the homogeneity of the electron emission from such layers is not uniform.